How to Become Invisible to Mosquitoes: A Computational Study of Host Signal Collapse

Mosquitoes locate vertebrate hosts by following coherent gradients of carbon dioxide, heat, and humidity. Nevertheless, a persistent empirical observation is that ordinary electric fans drastically reduce mosquito bites, even in the absence of chemical repellents. Here, we introduce a physics-guided, agent-based simulation demonstrating that mosquito host-seeking is not chemically inevitable but physically fragile. The model integrates directional airflow, vortex-induced chaotic mixing, and thermal decoy fields, and tracks 250 autonomous mosquito agents over 600 time-steps under Monte-Carlo sampling with independent randomized initializations. Three aerodynamic mechanisms were quantified. Mild upward airflow already reduces successful host localization by more than 80%, despite not mechanically preventing flight. Increasing vortex circulation produces a continuous, threshold-like collapse, reducing localization probability below 1% at moderate strength. Thermal decoys cause only a linear dilution of success, indicating misinformation alone cannot trigger collapse. A two-dimensional phase map reveals a robust "invisibility region" where airflow and vortex perturbations interact synergistically, eliminating host detection even when neither factor individually reaches threshold. These results show that mosquito host-seeking operates as a gradient-dependent failure system: once scalar fields lose spatial coherence, navigation collapses independent of sensory capability. This provides a quantitative theoretical basis for fan-mediated mosquito protection and suggests that non-chemical, low-energy airflow strategies can induce physical invisibility to hematophagous insects.